1. Field of the Invention
The invention relates to a wireless transmission device and, more particularly, to a computer system using the wireless transmission device.
2. Description of the Related Art
With the development of wireless communication technology, the latest wireless transmission standard develops to institute of electrical and electronics engineers (IEEE) 802.11n. The standard uses the multi-input multi-output (MIMO) technology, and it can improve data throughput and transmission distance of the communication system without increasing the bandwidth and the total transmit power expenditure.
The MIMO technology mainly uses the space freedom provided by several transmission antennas and receiving antennas to improve the spectrum efficiency of the wireless communication system and improve the transmission speed and optimize the communication quality. The computer system usually has two two-way transmission antennas to obtain the 2T2R or 1T2R wireless transmission function.
For example, FIG. 1 is a schematic diagram showing a conventional computer system with the wireless transmission function. A conventional computer system 100 includes a first housing 110 and a second housing 120 pivotally connected to the first housing 110. A display 130 is disposed in the first housing 110, and a motherboard 140 is disposed in the second housing 120. The wireless transmission module 150 may be a half mini card, and it may be connected to a slot of the motherboard 140 via a mini peripheral component interconnect (Mini PCI) connector (not show) to communicate with the motherboard 140. Furthermore, the wireless transmission module 150 also may be connected to cables 160 and 170 via an I-PEX connector (not shown), and connected to antennas 180 and 190 at the first housing 110 via the cables 160 and 170. Thus, the wireless transmission module 150 implements the 2T2R or 1T2R wireless signal transmission via the antennas 180 and 190 to provide the wireless transmission function needed by the computer system 100.
However, the structure of two two-way transmission antennas not only has higher cost due to the additional antennas, but also occupies the space for disposing the hardware of the computer system. The circuit board (including two connectors of the antennas) of the wireless transmission module is larger, and it is not favorable to a computer system pursuing a light and small outlook.
Besides the structure of two external antennas, the conventional computer system also uses a structure of single external antenna. FIG. 2 is a schematic diagram showing another conventional computer system with the wireless transmission function. In FIG. 2, a conventional computer system 200 includes a first housing 210 having a display 230 and a second housing 220 having a motherboard 240. A wireless transmission module 250 is disposed in the second housing 220, and connected to an antenna 270 at the first housing 210 via a cable 260. The wireless transmission module 250 implements the 1T1R wireless signal transmission via the antenna 270 to provide the wireless transmission function needed by the computer system 200.
Although the IEEE 802.11n standard supports the 1T1R wireless signal transmission, if only one antenna is disposed in the computer system, some access points (AP) using the IEEE 802.11n standard cannot demodulate the signal transmitted by single antenna, resulting in a great decreasement of the data transmission speed.